The present invention relates to a diagnostic device, such as a blood analyte meter, and a method of assembly of the same.
Hand held diagnostic devices are often used by patients for “self-testing” for the presence and/or concentrations of selected analytes in test samples. For example, a wide variety of hand held devices or “meters” are available to measure glucose concentrations in whole blood, thus enabling a diabetic to monitor his or her blood sugar level. These meters typically work in conjunction with test strips, the latter of which normally include a reaction chamber into which a reagent composition has been deposited and into which a sample of the patient's blood is drawn by capillary action.
Generally, these test strips and meters operate by optical methods or electrochemical methods. Optical methods generally involve spectroscopy to observe the spectrum shift in the fluid caused by concentration of the analyte, typically in conjunction with a reagent that produces a color change in the strip when combined with the analyte. Electrochemical methods generally rely upon the correlation between a current (amperometry), a potential (potentiometry) or accumulated charge (coulometry) and the concentration of the analyte, typically in conjunction with a reagent that produces charge-carriers when combined with the analyte. The diagnostic device makes the appropriate correlation and displays the result of the test, e.g., blood glucose concentration.
Current trends in such meters and test strips involve smaller test samples and faster analysis times. Accordingly, the size of test strips and the meters or devices which read them is also trending smaller. This provides a significant benefit to the patient, allowing the use of smaller blood samples that can be obtained from less sensitive areas of the body. Additionally, faster test times and more accurate results enable patients to better control their blood sugar level. Of course, smaller meters are less cumbersome and are able to be stored in small spaces, such as pockets in shirts or trousers, while allowing room for other traditional items such as car keys, coins and the like.
The trend toward smaller meters has introduced challenges in manufacturing. As the overall size of the meter decreases, the components within the meters also become smaller. The challenges arise in large scale assembly and in maintaining the ultimate structural integrity of the meter, e.g., its ability to withstand a drop test. These challenges are caused in part by the fact that as sizes become smaller, the number of fasteners such as screws and clips that can be used decreases as does the ability to efficiently install them during full scale manufacturing.
Similarly, the assembly of a meter is generally affected by the interconnection of the electrical circuitry, which is generally mounted onto flat, substantially two-dimensional circuit boards with attached components to carry, control, select, store and manipulate electronics signals. The greatest potential for system failure typically occurs at the location of the interconnections of the components, circuit boards and wiring assemblies. As meter size becomes smaller it becomes increasingly difficult to accurately align the components and maintain the connections secure, which in turn produces increased risk of failed connections.